Incandescent light bulbs are well known and have a metallic base and a glass envelope with a substantially hemisperical end or tip. Irrespective of whether the base is an Edision-Swan screw thread or a bayonet cap fitting, in order to change the light bulb it is necessary to apply a twisting force to the glass envelope in order to both engage and disengage the light bulb from its fitting.
Many people dislike changing light bulbs of this nature because of the need to grip the glass envelope in the hand. Whilst there is little likelihood of the bulb fracturing, there is some fear of this happening. In addition, the increasingly prevalent use of aluminum instead of brass in the base of the bulb has tended to increase problems caused by the bending or other malfunction of the base. A common fault is that the bond between the glass envelope and the base is broken.
A further problem is that from time to time persons changing such light bulbs are electrocuted owing to a breakdown in the electrical insulation of the bulb and/or the glass envelope fracturing and the person inadvertently coming into contact with the filament of the bulb which is inadvertently energised. A further problem is that most light fittings are in elevated positions and therefore it is necessary to climb upon a ladder, stool or small set of steps in order to reach the light fitting. In view of the above problems, a light bulb changing apparatus has been a desirable piece of equipment for some time and is normally mounted on a long rod in order to permit the operator to change the light bulb without the need to climb steps or the like.
Various types of light bulb changing appartaus are known and those disclosed in Australian Pat. Nos. 291,106 (45908/64) and 498,920 (78891/75) are typical of such arrangements in that they are relatively complex and include a number (usually three) of fingers which grip the glass envelope of the light bulb. Normally the fingers are moveable and are in some way able to be actuated from the (lower) end of the rod used to hold the fingers adjacent and elevated light fitting.
Such apparatus is characterised by being of relatively high mechanical complexity and therefore is not only costly but is also to some extent difficult to use, especially by unskilled labour.
Australian Pat. No. 278,135 (49755/64) discloses another light bulb changing apparatus which like the above described pieces of apparatus is complex to manufacture but grips the light bulb by a different means. In this apparatus the rod is provided with a rubber conical cup which is connected to a small air chamber in which the pressure is able to be either decreased to grip the bulb or increased to release the bulb from the apparatus.
In view of the foregoing it is an object of the present invention to provide an improved light bulb changing apparatus which is not mechanically complex and which is preferably adapted for manufacture by low cost plastics moulding so as to be able to produced at low cost.